The present invention relates to a method for the numerical storage of an analog curve of a system of rectangular coordinates X Y in a memory and plotting of a curve representative of this analog curve from the stored values.
It has already been proposed in the European Patent Specifications No. 0030234 to record handwriting speed signals, particularly of a reference signature, using a system of rectangular coordinates so as to enable the comparison of these signals with a further signature to ascertain whether the writer of the signature is the same in both cases. This comparison is designed to be carried out using computer techniques.
The characteristic speed signals of the reference are in general intended to be recorded in a memory formed by a magnetic stripe or a chip placed on a card which is normally in the possession of the cardholder. If the cardholder is not the writer of the signature, it would not be possible for this fraudulent cardholder to write a signature having speed signals comparable to those of the reference, even if he has practised copying the way in which the signature is written in an accurate way. Storage of the signature raises the problem of space, as the magnetic strip or chip has to contain other information. If it is desired to preserve the speed signals of the reference signature with sufficient accuracy, no memory card would have sufficient space for the storage of the analog speed signal data in a numerical form from which these signals could then be accurately reproduced. If the sampling carried out for storage does not provide sufficiently accurate information, the comparison carried out using this reference would be of little use since the reproduction of the reference for the purposes of the comparison would not provide an accurate picture of the genuine model.
The object of the present invention is to enable the accurate recording of these reference signals with a number of numerical data which is sufficiently small to be recorded either on a magnetic stripe or on a chip of a memory card of the credit card type.